Centrifugal pumps

ABSTRACT

A centrifugal pump for liquid has its rotor provided with a groove which acts as a scoop to urge liquid from the periphery of the pump casing into a gutter carried by the rotor. A tubular scoop extends into the gutter to discharge liquid within the gutter from an auxiliary outlet. The pump may this be effectively purged of liquid when shut down.

United States Patent 1 [11] 3,784,317

Lewis I Jan. 8, 1974 CENTRIFUGAL PUMPS 2,353,271 7/1944 Bowen ..415/l57 [75] Inventor: Geoffrey Art u L w s Solihull, 2,207,317 7/1940 Gear 415/109 warwlckshlre England FOREIGN PATENTS OR APPLICATIONS 1 1 Assigneer J p Lucas (Industries) Limited, 24,985 1907 Great Britain ..415/106 Birmingham, England 22 Filed: on. 26, 1971 Appl. No.2 192,265

Foreign Application Priority Data Oct. 27, 1970 Great Britain 50,877/70 US. Cl. 415/144, 415/89 Int. Cl F0411 l/l2 Field of Search 415/144, 98, 97,

References Cited UNITED STATES PATENTS 12/1964 Sence 415/106 Primary Examiner-Henry F. Raduazo Attorney-Holman & Stern ABSTRACT 7 Claims, 2 Drawing Figures 1 CENTRIFUGAL PUMPS This invention relates to centrifugal pumps of the type in which the pump inlet includes a control valve for throttling liquid flow through the pump.

In such pumps the outlet of the pump is usually so designed as to deliver liquid at a pressure corresponding to the static pressure within the casing and the kinetic pressure arising from the tangential velocity of the liquid is not fully employed. As a result, when the pump inlet is closed the delivery pressure falls rapidly to a low value and, if the pump is to be totally emptied when out of use, some low pressure sink has to be found. Emptying of the pump is of considerable importance in fuel systems for the gas turbine engines of high speed aircraft, where the amount of unnecessary energy dissipated into the fuel must be' kept as low as possible. If fuel is trapped in the centrifugal pump of the reheat fuel system, work will continuously be done on such fuel. Unfortunately, in aircraft applications of this type a low pressure sink cannot usually be found.

It is accordingly an object of the invention to provide a pump of the kind referred to in which emptying of the pump is facilitated.

A pump in accordance with the invention comprises a housing, an annular pump chamber inthe housing a valve controlled inlet opening into the inner part of the pump chamber, a main outlet opening into the outer part of the pump chamber, a rotor rotatably mounted in the housing and including at least one side plate and vanes on one side of said side plate, a groove in the other side of said side plate inclined to the periphery of the side plate at such an angle that, in use, liquid flows along said groove towards the axis of the rotor, a liquidcollecting gutter on the rotor for collecting liquid displaced inwardly by the groove an auxiliary outlet in the housing and a scoop member mounted on the housing and projecting into said gutter for displacing liquid from the gutter through said auxiliary outlet.

An example of the invention is illustrated in the accompanyingdrawings, in which:

FIG. 1 is a section through the pump, and

FIG. 2 is an enlarged fragmentary section on line 2-2 in FIG. 1.

The pump shown includes a housing having an annular pump chamber with a valve controlled inlet-11, a collecting channel 12 around the periphery of the chamber and a main outlet diffuser 13. A rotor 14 of the type having two side plates l5, 16 with vanes 17 between them isrotatably mounted in the housing on pressure-lubricated bearings 18, 19.

The side plate is formed adjacent its periphery with a groove 20 in the side thereof opposite the side having the vanes thereon. This groove follows a spiral path at a spiral angle such that, in use, the hydrodynamic forces on liquid in the groove 20 causing the liquid to flow towards the axis of the rotor'will exceed the outwardly acting centrifugal force on the liquid. To assist inward displacement of the liquid a lip 21 may be provided on the periphery of the side plate 15 on the downstream side of the groove 20.

Secured to the same side of the side plate 15 is a first gutter 22 which consists of an annular plate pressed to offset an outer flange 22a which is attached to the side plate. The groove 20 ends within this gutter so that any liquid passing inwardly along the groove 20 enters the gutter 22. The gutter 22 is connected by a tube 23 extending between the side plates 1.5, 16 to a second gutter 24 of similar design on the side plate 16.

A tubular scoop member 25 mounted on the housing 10 extends into the gutter 24 and, as shown, projects in a direction opposite the direction in which the gutter moves locally during rotation of the rotor 14. The scoop member 25 is connected to an auxiliary outlet 26.

The groove 20 assists in clearing the pump of liquid when the valve controlled inlet 11 is closed. The gutters 22, 24 also collect lubricant from the bearings 18, 19 flowing outwardly along the side plates 15, 16 respectively and ensure that this-liquid does not reach the channel 12, where it would be stirred by the rotor. The groove 20 extends, as shown in FIG. 2, at a relatively small angle to the tangent of the rotor 14. The groove 20, moreover, extends, as shown, over only a small fraction of the radialdimension of the rotor. Thus during its passage through the groove 20 a liquid has imparted to it only a small part of the velocity of the rotor, and centrifugal action on this liquid within groove 20 is therefore insufficient to arrest its inward flow. It will be understood that if the groove 20 was either longer or steeper, then a correspondingly larger amount of the rotor velocity would be imparted to a fluid within it.

I claim:

1. A pump comprising a housing, an annular pump chamber in the housing a valve controlled inlet opening into the inner part of the pump chamber, a main outlet opening into the outer part of the pump chamber, a rotor rotatably mounted on a pressure lubricated bearing in the housing and including at least one side plate adjacent said bearing and vanes on one side of said side plate, a groove in the other side of said side plate inclined to the periphery oppositely to the direction of rotation of said rotor in the side plate surface adjacent said bearing at such an angle that, in use, liquid flows along said groove from the periphery towards the axis of the rotor, a liquid collecting gutter on the rotor for collecting liquid displaced inwardly by the groove and outwardly by the lubricant, an auxiliary outlet in the housing and a scoop member mounted on the housing and projecting into said gutter for displacing liquid from the gutter through said'auxiliary outlet.

2. A pump as claimed in claiml in which said gutter is carried on said other side ofsaid side plate.

3. A pump as claimed in claim 2 in which said rotor includes a further side plate, said vanes, lying between downstream side of the groove. 

1. A pump comprising a housing, an annular pump chamber in the housing a valve controlled inlet opening into the inner part of the pump chamber, a main outlet opening into the outer part of the pump chamber, a rotor rotatably mounted on a pressure lubricated bearing in the housing and including at least one side plate adjacent said bearing and vanes on one side of said side plate, a groove in the other side of said side plate inclined to the periphery oppositely to the direction of rotation of said rotor in the side plate surface adjacent said bearing at such an angle that, in use, liquid flows along said groove from the periphery towards the axis of the rotor, a liquid collecting gutter on the rotor for collecting liquid displaced inwardly by the groove and outwardly by the lubricant, an auxiliary outlet in the housing and a scoop member mounted on the housing and projecting into said gutter for displacing liquid from the gutter through said auxiliary outlet.
 2. A pump as claimed in claim 1 in which said gutter is carried on said other side of said side plate.
 3. A pump as claimed in claim 2 in which said rotor includes a further side plate, said vanes lying between the side plates.
 4. A pump as claimed in claim 3 which includes a further gutter on said further plate on the side therof remote from said vanes.
 5. A pump as claimed in claim 4 which includes a passage interconnecting said gutters.
 6. A pump as claimed in claim 1 in which said groove follows a spiral path.
 7. A pump as claimed in claim 1 which includes a lip on the periphery of said one side plate adjacent the downstream side of the groove. 